Submerged multistage pump usable as propulsion unit

ABSTRACT

A submerged pump comprising a plurality of coaxial impellers arranged in series in an elongated casing having an inlet at one end and an outlet at the other and providing a pump chamber for each impeller and connecting passageways between the pump chambers, has additional inlets opening from the exterior of the casing into the connecting passageways between successive pump chambers. The velocity of liquid being pumped is increased by successive impellers and the volume of the liquid is increased by the liquid drawn in through the additional inlets. When used as a submerged propulsion unit the pump is of streamlined configuration and is surrounded by a shroud. Forward and reverse propulsion are selectively provided by directing the pump discharge to rearwardly or forwardly directed nozzles. The pump can also be used as a bow-thruster in a vessel.

United States Patent Ishiwata 1 July 25,1972

[54] SUBMERGED MULTISTAGE PUMP USABLE AS PROPULSION UNIT [2]] Appl. No.:69,800

FOREIGN PATENTS OR APPLICATIONS Germany ..415/199 147,227 5/1931 Germany..415/199 1,006,205 9/ 1965 Great Britain ..60/232 1,027,415 4/1966Great Britain ..60/232 Primary Examiner-Henry F. Raduazo Attorney-RobertE. Burns and Emmanuel J. Lobato [5 7] ABSTRACT A submerged pumpcomprising a plurality of coaxial impellers arranged in series in anelongated casing having an inlet at one end and an outlet at the otherand providing a pump chamber for each impeller and connectingpassageways between the pump chambers, has additional inlets openingfrom the exterior of the casing into the connecting passageways betweensuccessive pump chambers. The velocity of liquid being pumped isincreased by successive impellers and the volume of the liquid isincreased by the liquid drawn in through the addi tional inlets. Whenused as a submerged propulsion unit the pump is of streamlinedconfiguration and is surrounded by a shroud. Forward and reversepropulsion are selectively provided by directing the pump discharge torearwardly or forwardly directed novles. The pump can also be used as abow thruster in a vessel.

10 Claims, 10 Drawing Figures Patented July 25, 1972 3,678,689

5 Sheets-Sheet 2 Patented July 25, 1972 5 Sheets-Sheet 5 4 En llFIIIIIIIE Patented July 25, 1972 5 Sheets-Sheet 4 FIG 7 Patented July25, 1972 5 Sheets-Sheet 5 FIG. /0

FIG.9

SUBMERGED MULTISTAGE PUMP USABLE AS PROPULSION UNIT The presentinvention relates to pumps and particularly to multi-stage submergedpumps.

It is an object of the invention to provide a multistage submerged pumpof increased capacity and efficiency. A further object of the inventionis to provide a submerged pump which can be used as a propulsion unit insomewhat the same manner as a jet engine on aircraft, in which case itmay be provided with suitable reversing mechanisms. A further object ofthe invention is to provide a submerged pump which can be used as a bowthruster on a marine vessel to assist in maneuvering the vessel, forexample in docking.

In accordance with the invention. a plurality of spaced impellers arefixed on a rotating shaft extending longitudinally of an elongatedcasing which provides a pump chamber for each impeller. The casing hasan inlet at one end, an outlet at the other and passageways connectingthe successive pump chambers. Additional inlets opening from theexterior of the easing into the connecting passageways betweensuccessive pump chambers admit additional fluid so that the volume aswell as the velocity of the fluid is increased in its passage throughthe pump.

The pump in accordance with the invention can be used not only forpumping fluid from a supply to a discharge point but also as apropulsion unit, in which case the casing is streamlined and ispreferably surrounded by a shroud which is spaced from the casing toprovide an annular passageway between the casing and the shroud.Reversing means may be provided for directing the discharge of the pumpeither rearwardly or forwardly to provide propulsion alternatively in aforward or rearward direction.

The pump may also be used as a bow thruster unit installed in the bow ofa ship and provided with means for directing the discharge of the pumpselectively to either side so as to provide a lateral thrust on the bowof the ship.

The objects, characteristics and advantages of the invention will bemore fully understood from the following description of preferredembodiments shown by way of example in the accompanying drawings inwhich;

FIG. 1 is a side view partially in longitudinal section of a multistagesubmerged pump in accordance with the invention;

FIG. 2 is an end view of the left-hand end of the pump as viewed in FIG.1;

FIG. 3 is a side elevation partially in longitudinal section of asubmerged multi-stage pump in accordance with the invention used aspropulsion unit;

FIGS. 4 and 5 are half-end views of the inlet end and discharge endrespectively of the pump shown in FIG. 3, the other half being a mirrorimage of the half that is shown;

FIG. 6 is a partial longitudinal section of the discharge end portion ofa pump similar to that of FIG. 3 but showing reversing mechanism;

FIGS. 7 and 8 are half-end views of the inlet end and discharge endrespectively of a pump provided with reversing mechanism as shown inFIG. 6, the other half being a mirror image of the half that is shown;

FIG. 9 is a partial horizontal section illustrating the use of a pump inaccordance with the invention as a bow thruster of a marine vessel; and

FIG. 10 is a schematic side view illustrating a bow thrusterinstallation.

A pump in accordance with the invention as illustrated in FIGS. 1 and 2comprises an elongated casing I0 which is of circular cross-section andis shown as having a base portion 11. At one end, the casing is providedwith a suction inlet 12 while at the opposite end there is a discharge13. A rotatable shaft 15 extends longitudinally of the casing andprojects at one end for connection to a motor, turbine or other drivemeans providing suitable bearings for the shaft. A fluid-type sealbetween the casing 10 and the shaft 15 at the end where the shaftprojects is provided by a gland nut 16 applying pressure to packingrings 17 which bear on a sleeve 18 fixed on the shaft.

A plurality of impellers 21, 22, 23 and 24 spaced axially from oneanother by spacing sleeves 25 are secured on the shaft by an impellernut 26 and are keyed or otherwise fixed to the shaft for example by keysor pins 19, so as to rotate therewith. Each of the impellers has anannular passageway 27 having an inlet end 27a which opens approximatelyaxially toward the inlet end of the casing and a discharge end 27b whichopens approximately radially outwardly. As viewed in axial section, thepassageways 27 are generally .I-shaped with a short axial portion and alonger radial portion joined by a smooth curve. The annular passageway27 of each impeller is divided by a plurality of vanes 28 which extendradially outwardly from a point near the inlet end of the passage to thedischarge end. Depending on the design characteristics of the pump, thevanes 28 may be essentially radial or may be inclined, for examplespirally, in accordance with centrifugal pump design practice. Theimpellers are of progressively increasing size both axially and radiallywith the smallest impeller 21 at the inlet end of the casing and thelargest impeller 24 at the discharge end.

Diffusers 35, 36 and 37 divide the casing 10 into pump chambers 31, 32,33 and 34 which are of a size and shape to receive the impellers 21, 22,23 and 24 respectively with sufficient clearance to provide free runningof the impellers. The diffusers together with adjacent portions of thecasing provide connecting passageways 38 each of which connects thedischarge end 27b of the passageway 27 of a preceding impeller with theinlet 27a of a succeeding impeller. The pump chambers 31, 32, 33 and 34are thereby connected in series with one another so that fluid drawn inthrough the inlet 12 passes successively through the pump chambers 31,32, 33 and 34 and is discharged through the discharge 13. In the passageof the fluid through the pump, the velocity of the fluid isprogressively increased by the successive action of impellers 21, 22, 23and 24. Moreover, the crosssectional area of each of the connectingpassageways 38 decreases in the direction of flow of the fluid so thatthe velocity of the fluid is increased in passing from one pump chamberto the next.

In accordance with the invention, the diffusers 35, 36 and 37 togetherwith adjacent portions of the casing 10 provide additional inlets 40opening into the connecting passageways 38. The additional inletpassageways 40 are substantially annular, being interrupted byconnecting portions 41 which connect adjacent portions of the casing. Atthe points at which the inlet passages 40 merge with the connectingpassageways 38, the velocity of the fluid being pumped is sufficientlyhigh that its pressure is lower than that of the fluid in which the pumpis submerged so that additional fluid is drawn into the pump througheach of the additional inlet passages 40. Moreover, the inletpassageways 40 merge into the connecting passageways 38 in such a manneras to provide an injection effect to induce flow of fluid from the inletpassageways into the pump. Hence, in the passage of fluid through thepump, both its velocity and its volume are progressively increased withresulting increases in both the capacity and the efficiency of the pump.Guide vanes 42 are provided in the connecting passageways 38 andadjacent portions of the additional inlet passageways 40 so as to directthe fluid in the most efficient manner to the next succeeding impeller.The guide vanes 42 extend in a generally radial direction but may besomewhat inclined as desired to provide optimum operating characteristics of the pump.

The discharge 13 has a progressively increasing cross-sectional area sothat the velocity of the fluid discharged by the last impeller 24 is inpart converted to pressure.

For convenience of assembly, the casing 10 is made in two halves whichare assembled by means of flanges 43 and bolts 44 as seen in FIG. 2.

As illustrated in FIGS. 3-5, a submerged pump in accordance with thepresent invention can advantageously be used as a jet propulsion unitfor a marine vessel. The unit shown in FIGS. 3-5 comprises an elongatedstreamlined casing 50 having an inlet opening 51 at its forward end. Thecasing 50 is shown provided with a streamlined shroud 52 which surroundsthe casing with an annular space between the casing and the shroud. Theunit is mounted outboard of a vessel which it is to propel by means of asuitable support shown as a streamlined strut 53 projecting from thevessel. The casing and shroud are of circular cross-section and aregenerally of torpedo shape with the forward end smaller than themid-section and rear end to reduce resistance.

A shaft 55 is rotatably supported in the casing by bearings 56 and 57.Packing rings 58 provide a water-tight seal for the bearing 56 whilepacking rings 59 comprssed by a gland nut 60 provide a water-tight sealfor the bearing 57. The shaft 55 is driven by means of a beveled gear 61which is keyed or otherwise fixed on shaft and meshes with a beveledgear 62 fixed on a shaft 63 which extends outwardly from a power plantin the vessel through the strut 53. The driving shaft 63 is protected bya shroud 64.

A propeller 65 is fixed on the forward end of the shaft 55, for exampleby means of a key 66 and is secured by a nut 67 screwed onto a threadedend portion of the shaft. The propeller 65 rotates inside the inletpassage 51 at the forward end of the casing 50 and is preferably amulti-blade propeller having a diameter slightly less than the internaldiameter of the inlet passage so as to provide suitable clearance.Rearwardly of the propeller the inlet passage decreases in diameter andis provided with a plurality of radial guide vanes 68 which extend in anaxial direction. Rearwardly of the propeller 65, a plurality ofimpellers 71, 72 and 73 are secured on the shaft 55 for example by keys74 and are spaced axially from one another by sleeves 75 secured to thecasing for example by keys 76. Each of the impellers has a substantiallyannular fluid passageway 77 which has an inlet end opening forwardlynear the shaft 55 and which extends rearwardly and radially outwardlyfrom the inlet so as to provide a combined radial and axial flow. Theflow of fluid through the passageways 77 is guided by vanes 78 whichextend in a general axial and radial direction but may be inclined forexample in spiral form in accordance with accepted pump designs. Theimpellers are of progressively increasing size, the forwardmost impeller71 being the smallest and the rearwardmost impeller 73 being the largestso that they accelerate the increasing volume of fluid efficiently.

The casing 50 provides pump chambers for the impellers, each of thechambers being of suitable size and shape to accomodate the respectiveimpeller. Wear rings 79 are provided in the casing at the forward end ofeach of the impellers. The casing further provides an annular passageway81 connecting the discharge of impeller 71 with the inlet of impeller 72and an annular passageway 82 connecting the discharge of impeller 72with the inlet of impeller 73. The connecting passageways 81 and 82curve outwardly and then inwardly to provide smooth non-turbulent flowof the fluid from one impeller to the next. The cross-sectional area ofeach of the connecting passageways decreases in the direction flow so asto provide for increasing velocity and correspondingly decreasingpressure of the fluid. Flow of fluid through the connecting passageways81 and 82 is guided by circumferentially spaced vanes 83 which extend ina generally axial direction.

Additional substantially annular inlets 85 and 86 open into theconnecting passageways 81 and 82 slightly in advance of the impellers 72and 73 respectively so as to admit additional water to the pump. Theinlet end of the inlet passages 85 and 86 open forwardly so as toincrease the flow of water through the passageways by a ram effect.Moreover, the cross-sectional area of the annular space between thecasing 50 and the shroud 52 increases toward the rear from the inlet end52a of the shroud so that the fluid pressure inside the shroud increasesso as to increase the pressure differential between the liquid in thespace between the shroud and the casing and the liquid in the connectingpassageways 81 and 82 at the points where the inlet passageways 85 and86 open into them. The additional liquid entering through thepassageways 85 and 86 materially increases the capacity of the pump.

Liquid from the final impeller 73 is discharged through a substantiallyannular discharge passageway 88 into a diffusion chamber 89 at the rearof the casing. From the difiusion chamber the liquid is dischargedrearwardly through a plurality of diverging nozzles including a centralnozzle 90 and a surrounding array of noules 91. The central nozzle 90extends farther rearwardly than the surrounding nozzles 91. The nozzleassembly at the rear of the pump casing is surrounded by a tail ring 92which is spaced outwardly so as to provide an annular passageway 93between the tail ring and the rear end of the casing. Moreover, theleading edge of the tail ring 92 is spaced rearwardly from the trailingedge of the shroud 52 and is spaced radially outwardly of the trailingedge of the shroud so as to admit additional liquid to the passage 93.The flow of liquid through the passage 93 induced by the discharge fromthe noules 90, 91 augments the propulsive force provided by the unit.

In the operation of the propulsion unit shown in FIGS. 3 to 5, water isdrawn into the pump through the main inlet 51. Entry of water into thepump is assisted by the propeller 65 and by a ram effect which increasesas the speed of the unit through the water increases. The velocity ofthe water in the pump is progressively increased by the successiveimpellers 71, 72 and 73. Between successive impellers additional wateris introduced into the pump through the auxiliary inlet passageways 85,86. The entry of water through the auxiliary inlets is also increased bya ram effect as the speed of the unit through the water increases. Withthe construction shown and described, cavitation is effectively avoided.

The shroud 52 and the tail ring 92 are suitably supported with respectto the casing by longitudinally extending vanes 52b and 92arespectively.

In FIGS. 6-8, there is illustrated a modification of the propulsion unitshown in FIG. 3 in order to provide selectively either a forward or arearward thrust. In addition to rearwardly projecting nozzles 90 and 91which provide a forward thrust, a plurality of reversing nozzles 95extend laterally from the diffusion chamber 89 and each is rotatable bymeans of a hydraulic rotator 96 so as to be directed either rearwardlyor forwardly. Hydraulic fluid for operating the rotators is suppliedthrough control lines 97. The side nozzles are protected by side shrouds98 which are spaced outwardly from the main shroud 52 so as to providepassageways in which the nozzles 95 are located. The side shrouds 98improve streamlining of the unit and increase the effectiveness of thenozzles 95 by a diffusing technique.

A reversing valve disc 100 is movable axially in the diffusion chamber89 along a guide rod 101 by means of an actuating cylinder 102 fixed tothe reversing disc. The guide rod 101 is provided with a piston ring 103fitting closely in the cylinder 102 and with passageways 104 and 105opening respectively on opposite sides of the piston ring 103. Whenhydraulic fluid is supplied through the passageway 104, the reversingdisc 100 is moved rearwardly to the position shown in solid lines,thereby closing the rearwardly directed nozzles 90 and 91. Whenhydraulic fluid is supplied through the passageways 105, the reversingdisc is moved forwardly to the position shown in broken lines so thatthe rearwardly projecting nozzles 90 and 91 are open.

To provide forward propulsion, the reversing disc 100 is moved to itsforward (broken line) position and the side nozzles 95 are rotated so asto be directed rearwardly. Fluid from the diffusing chamber 89 isthereby discharged rearwardly through the nozzles 90 and 91 and alsothrough the side nozzles 95 to provide a propulsive force in a forwarddirection. To provide rearward propulsion, the reversing disc 100 ismoved to its rearward (solid line) position so as to close therearwardly directed nozzles 90 and 91 and the side nozzles 95 arerotated so as to be directed forwardly as shown in FIG. 6. Hence,pressure fluid from the diffusing chamber 89 discharged forwardlythrough the side nozzles 95 produces a rearwardly directed thrust.

FIGS. 9 and 10 illustrate the use of a propulsion unit in accordancewith the present invention as a bow thruster for a marine vessel. Asillustrated schematically in FIG. 10, a pump P which may be like thatshown in FIG. 3 is installed in the bow of a vessel V with its axisdisposed longitudinally of the vessel. Water is admitted to the pumpthrough an inlet passage 110 which opens forwardly in the bow of thevessel. The pump is surrounded by a substantially annular passageway [11which admits water to the additional side inlets of the pump. The pumpis driven from suitable power means through a shaft 109.

The output of the pump is conducted by a discharge tube 112 to athruster nozzle 115 which is disposed in a passageway 116 extendingtransversely through the bow of the vessel and is rotatable about theaxis of the discharge tube 112 so as to be directed selectively towardthe port or starboard side of the vessel. The nozzle 1 15 is rotatableby means of a control shaft 117 which provides control by the pilot orother personnel of the vessel. Packing glands 118 and 119 provide fluidtight seals to prevent leakage of water into the interior of the vessel.A streamlining portion 1 15a at the rear side of the nozzle 115 isprovided to improve the flow characteristics of liquid through thepassageway [16.

When the bow thruster pump P is operated with the node 115 in theposition shown in FIG. 9, water is discharged from the nozzle 115 towardthe port side of the vessel and induces additional flow of water throughthe passageway 116 so as to produce a thrust on the bow of the vesseltending to move it in a starboard direction. When the nozzle is rotated180 by means of the control shaft 117 so as to be directed toward thestarboard side of the vessel, operation of the pump P results in theproduction of a thrust toward the port side of the vessel in likemanner. It will be understood that the pump and the nozzle 115 aresuitabley controlled from the pilot house or other convenient locationon the vessel.

While preferred embodiments of the invention have been shown by way ofexample in the drawings and are herein specifically described, it willbe understood that modifications may be made according to therequirements of particular applications of the pump. For example, if ahigher discharge pressure is desired, the final stage of the pump maycomprise two or more impellers operating in series without additionalinlet passages between them. For each application, the number of stagesand other parameters of the pump are selected in accordance with designrequirements.

What 1 claim is:

l. A submerged propulsion unit comprising an elongated streamlinedcasing having forwardly facing front inlet at the forward end and a jetdischarge outlet at the rearward end, a rotatable shalt extendinglongitudinally of said casing, a plurality of impellers fixed on saidshaft and spaced axially from one another, means in said casing defininga pump chamber for each of said impellers, intermediate passagewaysconnecting successive pump chambers with one another, an inlet passageconnecting the inlet of said casing with the first of said plurality ofpump chambers and a discharge passage connecting the last of saidplurality of pump chambers with said outlet of said casing, said pumpcasing having at least one intermediate inlet which faces forwardly ofsaid casing and is connected with a respective intermediate passage,said impellers upon rotation by said shaft drawing fluid in through saidfront inlet and said intermediate inlet, impelling it rearwardly withprogressively increasing velocity and discharging it from said outlet,the volume of said fluid being progressively increased by additionalfluid drawn in through :said intermediate inlet and said impellersincreasing in size from the front toward the rear of said casing tohandle said progressively increasing volume of fluid.

2. A fluid pump according to claim 1 in which said intermediatepassageways are annular.

3. A fluid pump according to claim 2, in which said intermediate inletsare annular.

4. A fluid pump according to claim 2, in which each said annularintermediate passageway leads from a radially outer portion of apreceding pump chamber to a radially inner portion of a succeeding pumpchamber.

5. A propulsion unit according to claim 1, comprising a shroudsurrounding and spaced from said casing to define an annular passagebetween said shroud and casing, said intermediate inlet openingforwardly from said annular passageway into said intermediatepassageway, whereby fluid is forced into said intermediate inlet by theram effect of fluid flowing through said annular passage.

6. A propulsion unit according to claim 5, in which a tail ringsurrounds and isspaced from a rear end portion of said casing to definean annular passage between said casing and said tail ring and to inducea fast-moving flow of fluid in the space between the shroud and casingto increase the ram effect on said intermediate inlet or inlets andthereby draw more water in through said intermediate inlets.

7. A propulsion unit according to claim 1, in which said outletcomprises a central rearwardly directed nozzle and a plurality ofrearwardly directed nozzles arranged around said central nozzle.

8. A propulsion unit according to claim 1, in which said outletcomprises at least one rearwardly directed nozzle and at least oneforwardly directed nozzle, and in which flow directing means is operableto direct discharge fluid selectively to said rearwardly directed nozzleto provide a forward propulsion force or to said rearwardly directednozzle to provide a rearwardly propulsion force.

9. A propulsion unit according to claim 1, in which said outletcomprises a nozzle directed laterally of said pump to provide alaterally directed reaction force from the discharge of fluid from saidnozzle, said nozzle being rotatable about the longitudinal axis of saidpump to control the direction of said reaction force.

10. A propulsion unit according to claim 16, in which a forwardly facingannular intermediate inlet is provided opening into each of saidintermediate passageways.

1. A submerged propulsion unit comprising an elongated streamlinedcasing having forwardly facing front inlet at the forward end and a jetdischarge outlet at the rearward end, a rotatable shaft extendinglongitudinally of said casing, a plurality of impellers fixed on saidshaft and spaced axially from one another, means in said casing defininga pump chamber for each of said impellers, intermediate passagewaysconnecting successive pump chambers with one another, an inlet passageconnecting the inlet of said casing with the first of said plurality ofpump chambers and a discharge passage connecting the last of saidplurality of pump chambers with said outlet of said casing, said pumpcasing having at least one intermediate inlet which faces forwardly ofsaid casing and is connected with a respective intermediate passage,said impellers upon rotation by said shaft drawing fluid in through saidfront inlet and said intermediate inlet, impelling it rearwardly withprogressively increasing velocity and discharging it from said outlet,the volume of said fluid being progressively increased by additionalfluid drawn in through said intermediate inlet and said impellersincreasing in size from the front toward the rear of said casing tohandle said progressively increasing volume of fluid.
 2. A fluid pumpaccording to claim 1 in which said intermediate passageways are annular.3. A fluid pump according to claim 2, in which said intermediate inletsare annular.
 4. A fluid pump according to claim 2, in which each saidannular intermediate passageway leads from a radially outer portion of apreceding pump chamber to a radially inner portion of a succeeding pumpchamber.
 5. A propulsion unit according to claim 1, comprising a shroudsurrounding and spaced from said casing to define an annular passagebetween said shroud and casing, said intermediate inlet openingforwardly from said annular passageway into said intermediatepassageway, whereby fluid is forced into said intermediate inlet by theram effect of fluid flowing through said annular passage.
 6. Apropulsion unit according to claim 5, in which a tail ring surrounds andis spaced from a rear end portion of said casing to define an annularpassage between said casing and said tail ring and to induce afast-moving flow of fluid in the space between the shroud and casing toincrease the ram effect on said intermediate inlet or inlets and therebydraw more water in through said intermediate inlets.
 7. A propulsionunit according to claim 1, in which said outlet comprises a centralrearwardly directed nozzle and a plurality of rearwardly directednozzles arranged around said central nozzle.
 8. A propulsion unitaccording to claim 1, in which said outlet comprises at least onerearwardly directed nozzle and at least one forwardly directed nozzle,and in which flow directing means is operable to direct discharge fluidselectively to said rearwardly directed nozzle to provide a forwaRdpropulsion force or to said rearwardly directed nozzle to provide arearwardly propulsion force.
 9. A propulsion unit according to claim 1,in which said outlet comprises a nozzle directed laterally of said pumpto provide a laterally directed reaction force from the discharge offluid from said nozzle, said nozzle being rotatable about thelongitudinal axis of said pump to control the direction of said reactionforce.
 10. A propulsion unit according to claim 16, in which a forwardlyfacing annular intermediate inlet is provided opening into each of saidintermediate passageways.